How do I replace a damaged valve on a water heater?

Question

Near the bottom of my hot water tank there is a plastic valve that looks like it is used for draining the water out of it. It has developed a hairline fracture along the length of it and small jets of hot water were shooting out of it.

I've shut off the cold water supply valve and turned off the gas running to the hot water tank. My plan is to drain the hot water tank and replace the valve. However I do not know if this is some sort of special valve and if there is anything extra I would need to do with it's replacement besides just screwing it in.

What kind of valve should I be asking for at my local hardware store and how do I replace this valve?

Answer 1

It should be a standard threaded valve (NPT, National Pipe Tread), most likely 1/2" in diameter. If you are not sure, you can do one of the following:

1. Lookup the valve in the manual, search the make and model on line if you don't have a hard copy of it.
2. Remove the valve and take it to the store with you.

Two would be the simplest.

When draining the tank, remember to open the hot side of a fixture or two as this is will allow air to enter the system and let the tank drain faster. You can keep these fixtures open until you refill the tank as they will allow the air to leave the system when filling the tank.